Use of fumaric acid derivatives for treating mitochondrial diseases

ABSTRACT

The present invention relates to the use of individual fumaric acid derivatives or mixtures thereof for preparing a pharmaceutical composition for treating mitochondrial diseases, especially for treating Parkinson&#39;s syndrome, Alzheimer&#39;s disease, Chorea Huntington disease, retinopathia pigmentosa and mitochondrial encephalomyopathy. Preferably, the fumaric acid derivative(s) is/are those selected from the group consisting of fumaric acid dialkyl esters or fumaric acid monoalkyl esters in the form of the free acid or a salt thereof.

[0001] The present invention relates to the use of individual fumaric acid derivatives or mixtures thereof for preparing a pharmaceutical composition for treating mitochondrial diseases, especially for treating Parkinson's syndrome, Alzheimer's disease, Chorea Huntington disease, retinopathia pigmentosa and mitochondrial encephalomyopathy.

[0002] The mitochondria have an independent genetic system of DNA (mtDNA) and RNA and are therefore able to synthesise certain proteins on their own. Both genes of the cell nucleus and the mitochondrial genome code for the components of oxidative phosophorylation and the citrate cycle. A genetic defect of the mtDNA may therefore affect oxidative phosphorylation and the citrate cycle, respectively, and cause malfunctions. Such defects or malfunctions have been associated with the so-called mitochondrial diseases.

[0003] Genetic defects of mtDNA may be the result of local mutation by which one base is replaced by another. Such point mutations are associated with neurogenetic myasthenia, ataxia and retinopathia pigmentosa, for example.

[0004] Genetic defects of the mtDNA may also be caused by insertion or deletion mutation where one or more nucleotides are inserted into or deleted from the DNA. This mutation mechanism is being discussed in connection with the Kearns Sayre syndrome and the Pearson syndrome.

[0005] The mutation of mtDNA also plays a role in neurodegenerative diseases such as Parkinson syndrome, Alzheimer's disease or Chorea Huntington disease (Encyclopedia of Molecular Biology and Molecular Medicine, Vol., 4, Ed. R. A. Meyers). However, it has not been possible to allocate the causative mutations to these diseases without any doubt so far. For example, an accumulation of mutations is also being discussed as a basis of pathogenesis.

[0006] The Parkinson syndrome exhibits a number of symptoms which may be divided into three groups. Motoric disorders are expressed by the plus symptoms rigor (increased tonus of the striated musculature) and medium to heavy tremor (twitching in rapid succession) and the minus symptom hypokinesia or akinesia (deterioration of the motor system, loss of postural reflexes). Vegetative symptoms (increased flow of saliva and tears, post-encephalitic seborrhoea) and psychic disorders (increased indecisiveness, depressive moods, etc.) are also being observed.

[0007] The disease is based on a destruction of nerve cells in the motoric key areas of the brain stem. In Germany, for example, about 200,000 patients are affected. At molecular level, the Parkinson syndrome is associated, among other things, with mutations of the mitochondrial genome. It has been possible to show mtDNA deletions in Parkinson patients. In addition, a dopamine insufficiency of certain regions of the brain is found in cases of Parkinson syndrome. The symptoms observed are an expression of the impaired balance between the neurohumoral transmitter substances acetyl choline and dopamine.

[0008] At present, drug therapies are based on the inhibition of cholinergic neurotransmission with centrally acting anticholinergics, the increase of the dopamine concentration by administration of the dopamine precursor Levodopa and the stimulation of central dopamine receptors with direct dopaminergic agonists.

[0009] Specific therapies therefore comprise the administration of anticholinergics or of Levodopa. In order to favourably influence both the plus symptoms and the minus symptom in Parkinson patients, a combination therapy is usually required which is supplemented by non-drug therapeutic measures.

[0010] On the other hand, a therapy with anticholinergics is inadvisable for Parkinson patients already suffering from marked psycho-organic disorders or exogenpsychotic symptoms, because a worsening of the symptoms must be expected.

[0011] Side effects limiting the therapeutic use of Levodopa are motoric symptoms (hyperkinesia, dyskinesia), vegetative disorders (gastro-intestinal problems, among others) and cardiovascular disorders (such as orthostatic disorders).

[0012] Alzheimer's disease is pre-senile or senile dementia which progresses irreversibly and which is characterised by the destruction of areas of the brain. Recent studies show that, in addition to mitochondrial genetic defects, the increased presence of the apolipoprotein E₄ (apo E₄) is related to the occurrence of Alzheimer's disease. In the hereditary form of this disease, the corresponding gene for the apo E₄ is often defective. As opposed to the Parkinson syndrome, no therapy other than treatment with indomethacin is available for Alzheimer's disease. However, indomethacin also has considerable side effects.

[0013] Retinopathia pigmentosa is a degenerative process which is more often hereditary than acquired. It is associated with a narrowing of the retinal vessels, opticus atrophy, the destruction of neural elements of the retina and a deposition of pigments. Symptoms are nyctalopia, a severe narrowing of the field of vision and loss of sight.

[0014] Mitochondrial encephalomyopathy is a disease characterised by disorders of the mitochondrial respiratory chain. Typical symptoms are myopathy (so-called ragged red fibres myopathy), stunted growth, dementia, epileptic episodes, ataxia, focal neurological disorders and MELAS (mitochondrial encephalomyopathy, lactate acidosis and strokes).

[0015] Chorea Huntington is a hereditary dominant autosomal disease with a defect on the short arm of the 4^(th) chromosome which usually becomes manifest between the ages of 30 and 50 and is associated with progressive dementia. A defect or atrophy of the nucleus candatus and possibly the nucleus lentiformis may be named as possible causes. A defect of the neurotransmitter metabolism and the influence of mtDNA defects are under discussion.

[0016] Therefore, it is an object of the invention to provide a pharmaceutical composition for the treatment of mitochondrial diseases, especially those described above, and to permit partial treatment of these diseases with drugs, which has not been possible so far. It is another object of the invention to provide a pharmaceutical preparation for the treatment of the above diseases which reduces the side effects of existing drug therapies and does not require a combination therapy.

[0017] The object of the present invention is achieved by the use of individual or a mixture of fumaric acid derivative(s) for preparing a pharmaceutical composition for treating mitochondrial diseases, especially for treating Alzheimer's disease, Parkinson's syndrome, Chorea Huntington disease, retinopathia pigmentosa and mitochondrial encephalomyopathy. The subject matters of the invention are characterised in detail in the claims.

[0018] It is known that pharmaceutical preparations which, upon biological degradation after administration, enter into the citric acid cycle or are part thereof gain increasing therapeutic significance—especially when given in high dosages—since they can alleviate or heal diseases caused cryptogenetically.

[0019] For example, fumaric acid inhibits the growth of the Ehrlich ascites tumour in mice, reduces the toxic effects of mitomycin C and aflatoxin and displays anti-psoriatic and anti-microbial activity. In general, the treatment of psoriasis with different fumaric acid derivatives has already been described in a number of patents, e.g. EP 0 188 749, DE 25 30 372, DE 26 21 214 or EP 0 312 697.

[0020] Another use of certain fumaric acid derivatives, namely of the alkyl hydrogen fumarates, is disclosed in DE 197 21 099.6 and DE 198 53 487.6 according to which these specific fumaric acid derivatives are described for treating autoimmune diseases such as polyarthritis, multiple sclerosis and graft-versus-host reactions. In addition, DE 198 53 487.6 and DE 198 39 566.3 teach the use of alkyl hydrogen fumarates and dialkyl fumarates in transplantation medicine.

[0021] Surprisingly, it has now been found that individual fumaric acid derivatives or mixtures thereof may advantageously be used for preparing a pharmaceutical preparation for treating mitochondrial diseases, especially for treating the Parkinson syndrome, Alzheimer's disease, Chorea-Huntington disease, retinopathia pigmentosa or mitochondrial encephalomyopathy.

[0022] In the invention, one or more fumaric acid dialkyl esters and/or fumaric acid monoalkyl esters in the form of the free acid or in the salt form are preferably used for preparing the pharmaceutical composition.

[0023] The fumaric acid dialkyl esters preferably correspond to the formula

[0024] wherein R₁ and R₂ which may be the same or different independently represent a linear, branched, saturated or unsaturated C₁₋₂₄ alkyl radical or a C₅₋₅₀ aryl radical and wherein these radicals are optionally substituted with halogen (F, Cl, Br, I), hydroxy, C₁₋₄ alkoxy, nitro or cyano.

[0025] The radicals R₁ and R₂ preferably are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, pentyl, cyclopentyl, 2-ethylhexyl, hexyl, cyclohexyl, heptyl, cycloheptyl, octyl, vinyl, allyl, 2-hydroxyethyl, 2- and/or 3-hydroxypropyl, 2-methoxyethyl, methoxymethyl or 2- or 3-methoxypropyl.

[0026] The fumaric acid monoalkyl esters preferably correspond to the formula

[0027] wherein R₁ is a radical as defined above; A is hydrogen or an alkaline or alkaline earth metal cation or a physiologically acceptable transition metal cation, preferably selected from Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Zn²⁺, Fe²⁺,Mn²⁺ and n is 1 or 2 and corresponds to the valence of A.

[0028] Preferably the fumaric acid derivatives of the invention are used in such an amount that one dosage unit of the pharmaceutical composition contains an amount of one or more fumaric acid derivative(s) which corresponds or is equivalent to 1 to 500 mg, preferably 10 to 300 mg and most preferably 10 to 200 mg of fumaric acid.

[0029] Applications are preferred where the pharmaceutical composition is administered orally, parenterally, rectally, transdermal or ophthally (in the form of eye drops), oral administration being preferred. The preparation is present in the form suitable for the pertinent form of administration.

[0030] In case of oral administration the pharmaceutical composition of the invention is present in the form of unit dosage tablets, micro-tablets or micro-tablets (micro-pellets) or granulate which may optionally be encapsulated or filled into sachets, capsules or solutions for drinking.

[0031] In a preferred embodiment, solid dosage forms or forms of administration, respectively, are provided with an enteric coating. Such a coating may also be applied to the encapsulated or filled dosage forms.

[0032] According to the invention, one or more fumaric acid derivative(s) is/are preferably used which are selected from the group comprising fumaric acid dimethyl ester, fumaric acid diethyl ester, fumaric acid methyl ethyl ester, methyl hydrogen fumarate, ethyl hydrogen fumarate, magnesium methyl fumarate, magnesium ethyl fumarate, zinc methyl fumarate, zinc ethyl fumarate, iron methyl fumarate, iron ethyl fumarate, calcium methyl fumarate and/or calcium ethyl fumarate.

[0033] The pharmaceutical composition of the invention may preferably contain 10 to 500 mg of dialkyl fumarate, especially dimethyl fumarate and/or diethyl fumarate; 10 to 500 mg of calcium alkyl fumarate, especially calcium methyl fumarate and/or calcium ethyl fumarate, 0 to 250 mg of zinc alkyl fumarate, especially zinc methyl fumarate and/or zinc ethyl fumarate, 0 to 250 mg of alkyl hydrogen fumarate, especially methyl hydrogen fumarate and/or ethyl hydrogen fumarate and 0 to 250 mg of magnesium alkyl fumarate, especially magnesium methyl fumarate and/or magnesium ethyl fumarate; the total of the amounts specified corresponding to an equivalent of 500 mg, preferably 300 mg and most preferably 200 mg of fumaric acid.

[0034] Preferred compositions according to the invention contain only methyl hydrogen fumarate or dimethyl fumarate in an amount of 10 to 300 mg.

[0035] For example, the fumaric acid derivatives are prepared according to the method described in EP 0 312 679.

[0036] In order to illustrate the use according to the invention, various examples for preparing preferred drugs are given below.

EXAMPLE 1 Preparation of Film Tablets with an Enteric Coating Containing 100.0 mg of Monomethyl Fumarate-Ca Salt, which Corresponds to 78 mg of Fumaric Acid

[0037] Taking the necessary precautions (breathing mask, gloves, protective clothing, etc.), 10.000 kg of monomethyl fumarate-Ca salt are crushed, mixed intensely and homogenised by means of a sieve 800. Then an excipient mixture of the following composition is prepared: 21.000 kg of starch derivative (STA-RX 1500®), 2.000 kg of micro-crystalline cellulose (Avicel PH 101®), 0.600 kg of polyvinyl pyrrolidone (PVP, Kollidon® 25), 4.000 kg of Primogel®, 0.300 kg of colloidal silicic acid (Aerosil®).

[0038] The active ingredient is added to the entire powder mixture, mixed, homogenised by means of a sieve 200 and processed with a 2% aqueous solution of polyvinyl pyrrolidone (PVP, Kollidon®25) in the usual manner into binder granules, and then mixed with the outer phase in a dry state. The latter consists of 2.000 kg of a so-called FST complex containing 80% of talcum, 10% of silicic acid and 10% of magnesium stearate.

[0039] Thereafter the mixture is pressed into convex tablets with a weight of 400 mg and a diameter of 10.0 mm by the usual method. Instead of these classic compaction methods, other methods such as direct compaction or solid dispersions according to the melting and spray drying method may also be used for preparing tablets.

[0040] Enteric Coating:

[0041] A solution of 2.250 kg of hydroxy propyl methyl cellulose phthalate (HPMCP, Pharmacoat HP® 50) is dissolved in a solvent mixture consisting of 2.50 liters of demineralised water, 13.00 liters of acetone Ph. Helv. VII and 13.00 liters of ethanol (94% by weight) and then 0.240 kg of castor oil (Ph. Eur. II) is added to the solution. The solution is poured or sprayed in portions onto the tablet cores in a coating pan in a conventional manner or applied by means of a fluidised-bed apparatus of the appropriate structure.

[0042] After drying, the film coating is applied. Said coating consists of a solution of Eudragit E 12.5%® 4.800 kg, talcum Ph. Eur. II 0.340 kg, titanium(VI) oxide Cronus RN 56® 0.520 kg, coloured lacquer ZLT-2 blue (Siegle) 0.210 kg, and polyethylene glycol 6000 Ph. Helv. VII 0.12 kg in a solvent mixture of 8.200 kg of 2-propanol Ph. Helv. VII, 0.06 kg of glycerine triacetate (Triacetin®) and 0.200 kg of demineralised water. After homogenous distribution in the coating pan or the fluidised bed, the mixture is dried and polished in the usual manner.

EXAMPLE 2 Preparation of Enteric Coated Capsules Containing 86.5 mg of Monoethyl Fumarate-Ca Salt and 110.0 mg of Dimethyl Fumarate, which Corresponds to a Total of 150 mg of Fumaric Acid

[0043] Taking the necessary precautions (breathing mask, gloves, protective clothing, etc.), 8.650 kg of monoethyl fumarate-Ca salt and 11.000 kg of dimethyl fumarate are intensely mixed with a mixture consisting of 15.000 kg of starch, 6 kg of lactose Ph. Helv. VII, 2 kg of micro-crystalline cellulose (Avicel®), 1 kg of polyvinyl pyrrolidone (Kollidon® 25) and 4 kg of Primogel® and homogenised by means of a sieve 800.

[0044] Together with a 2% aqueous solution of polyvinyl pyrrolidone (Kollidon® 25) the entire powder mixture is processed in the usual manner into a binder granulate and mixed with the outer phase in the dried state. Said outer phase consists of 0.350 kg of colloidal silicic acid (Aerosil®), 0.500 kg of Mg stearate and 1.500 kg of talcum Ph. Helv. VII. The homogeneous mixture is then filled in portions of 500.0 mg into appropriate capsules which are then provided with an enteric (gastric-acid resistant) coating consisting of hydroxy propyl ethyl cellulose stearate and castor oil as softening agent by a known method. Instead of hard gelatine capsules, the mixture may also be filled into appropriate gastric acid-resistant capsules, which consist of a mixture of cellulose acetate phthalate (CAP) and hydroxy propyl ethyl cellulose phthalate (HPMCP).

EXAMPLE 3 Preparation of Enteric-coated Micro-tablets in Capsules Containing 87.0 mg of Monoethyl Fumarate-Ca Salt, 120 mg of Dimethyl Fumarate, 5.0 mg of Monoethyl Fumarate-Mg Salt and 3.0 mg of Monoethyl Fumarate-Zn Salt, which Corresponds to a Total of 164 mg of Fumaric Acid (“forte” Tablets)

[0045] Taking the necessary precautions (breathing mask, gloves, protective clothing, etc.), 8.700 kg of monoethyl fumarate-Ca salt, 12.000 kg of dimethyl fumarate 0.500 kg of monoethyl fumarate-Mg salt and 0.300 kg of monoethyl fumarate-Zn salt are crushed, intensely mixed and homogenised by means of an sieve 800. Then an excipient mixture of the following composition is prepared: 18.00 kg of starch derivative (STA-RX 1500), 0.30 kg of micro-crystalline cellulose (Avicel PH 101), 0.75 kg of PVP (Kollidon 120), 4.00 kg of Primogel, 0.25 kg of colloidal silicic acid (Aerosil). The entire powder mixture is added to the active ingredient mixture, homogenised by means of a 200 sieve, processed in the usual manner with a 2% aqueous solution of polyvinyl pyrrolidone (Kollidon K25) to obtain a binder granulate and mixed in a dry state with the outer phase consisting of 0.50 kg of magnesium stearate and 1.50 kg of talcum. Then the powder mixture is pressed by the conventional method into convex micro-tablets with a gross mass of 10.0 mg and a diameter of 2.0 mm. Instead of this classic tabletting method other methods for making tablets such as direct tabletting or solid dispersions by the melt method and the spray drying method may also be used.

[0046] The gastric acid-resistant coating may be poured or sprayed on in a classic coating pan or applied in a fluidised-bed apparatus. In order to achieve resistance to gastric acid, portions of a solution of 2.250 kg of hydroxy propyl methyl cellulose phthalate (HPMCP, Pharmacoat HP 50) are dissolved in a mixture of the following solvents: acetone 13.00 l, ethanol 94% by weight denatured with 2% ketone 13.50 l and demineralised water 2.50 l. 0.240 kg of castor oil are added as softening agent to the finished solution and applied in portions to the tablet cores in the usual manner.

[0047] Film-coat: After drying is completed, a suspension of the following composition is applied as a film-coat in the same apparatus: talcum 0.340 kg, titanium(VI) oxide Cronus RN 56 0.4 kg, coloured lacquer L red lacquer 86837 0.324 kg, Eudragit E 12.5% 4.800 kg and polyethylene glycol 6000 pH 11 XI 0.12 kg in a solvent mixture of the following composition: 2-propanol 8.170 kg, aqua demineralisata 0.20 kg and glycerine triacetate (Triacetin) 0.600 kg.

[0048] The gastric acid-resistant micro-tablets are then filled into hard gelatine capsules at a net weight of 500.0 mg and sealed.

EXAMPLE 4

[0049] Example 4 shows the stimulating influence of fumaric acid derivatives on the enzyme activity of succinate dehydrogenase.

[0050] Succinate dehydrogenase is part of the mitochondrial membrane and catalyses the dehydration of succinic acid to fumaric acid within the citrate cycle. Hydrogen is passed to the respiratory chain via the electron transfer flavoprotein. Thus, the activity of succinate dehydrogenase may influence the electron flow of the electron transport chain. The latter, in turn, is linked to the process of oxidative phosphorylation, the malfunction of which is considered a cause for mitochondrial diseases. Consequently, the activity of succinate dehydrogenase may also have an effect on oxidative phosphorylation.

[0051] The following table 1 shows an evaluation of the stimulating influence of fumaric acid derivatives on the enzyme activity of the succinate dehydrogenase. Fumarates Fibroblasts [0.75 m Val/I] Dimethyl fumarate strong (838%) Calcium monoethyl fumarate medium Magnesium monoethyl fumarate weak Zinc monoethyl fumarate strong (107%) Monoethyl fumarate weak 

1. The use of individual or a mixture of fumaric acid derivatives for preparing a pharmaceutical composition for treating mitochondrial diseases.
 2. The use according to claim 1, characterised in that the fumaric acid derivatives are those selected from the group consisting of fumaric acid dialkyl esters and fumaric acid monoalkyl esters in the form of the free acid or a salt thereof.
 3. The use according to claim 2 where the fumaric acid dialkyl ester corresponds to the formula

wherein R₁ and R₂ which may be the same or different independently represent a linear, branched, cyclic, saturated or unsaturated C₁₋₂₄ alkyl radical or a C₅₋₂₀ aryl radical and wherein these radicals are optionally substituted with halogen (F, Cl, Br, I), Hydroxy, C₁₋₄ alkoxy, nitro or cyano.
 4. The use according to any of the claims 2 or 3, characterised in that the radicals R₁ and R₂ are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, pentyl, cyclopentyl, 2-ethylhexyl, hexyl, cyclohexyl, heptyl, cycloheptyl, octyl, vinyl, allyl, 2-hydroxyethyl, 2- and/or 3-hydroxypropyl, 2-methoxyethyl, methoxymethyl or 2- or 3-methoxypropyl.
 5. The use according to claim 2 wherein the fumaric acid monoalkyl ester corresponds to the formula

wherein R₁ is as defined in claims 3 or 4, A is hydrogen or an alkaline or alkaline earth metal cation or a physiologically acceptable transition metal cation, preferably selected from Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, Zn²⁺, Mn²⁺ and n is 1 or 2 and corresponds to the valence of A.
 6. The use according to any of the claims 1 to 5, characterised in that one dosage unit of the pharmaceutical composition contains an amount of fumaric acid derivative(s) which corresponds to 1 to 500 mg, preferably 10 to 300 mg and most preferably 10 to 200 mg of fumaric acid.
 7. The use according to any of the previous claims for preparing a pharmaceutical composition for oral, parenteral, rectal, transdermal or ophthal administration, preferably for oral administration.
 8. The use according to claim 7 where the pharmaceutical composition for oral administration is present in the form of unit dosage tablets, micro-tablets or micro-tablets optionally encapsulated or filled into sachets [(micro-pellets) or granulate], capsules or solutions for drinking.
 9. The use according to claim 8, characterised in that the solid dosage forms are provided with an enteric coating.
 10. The use according to any of the previous claims, characterised in that the fumaric acid derivative is one or more selected from the group comprising fumaric acid dimethyl ester, fumaric acid diethyl ester, fumaric acid methyl ethyl ester, methyl hydrogen fumarate, ethyl hydrogen fumarate, calcium methyl fumarate, calcium ethyl fumarate, magnesium methyl fumarate, magnesium ethyl fumarate, zinc methyl fumarate, zinc ethyl fumarate, iron methyl fumarate and/or iron ethyl fumarate.
 11. The use according to claim 10, characterised in that the dosage units of the pharmaceutical composition obtained preferably contain either individually or in a mixture: 10 to 500 mg of dialkyl fumarate, especially dimethyl fumarate and/or diethyl fumarate; 10 to 500 mg of calcium alkyl fumarate, especially calcium methyl fu- marate and/or calcium ethyl fumarate; 0 to 250 mg of zinc alkyl fumarate, especially zinc methyl fumarate and/or zinc ethyl fumarate; 0 to 250 mg of alkyl hydrogen fumarate, especially methyl hydrogen fumarate and/or ethyl hydrogen fumarate, and 0 to 250 mg of magnesium alkyl fumarate, especially magnesium methyl fumarate and/or magnesium ethyl fumarate


12. The use according to any of the previous claims, characterised in that the mitochondrial diseases are Parkinson's syndrome, Alzheimer's disease, Chorea Huntington disease, retinopathia pigmentosa or mitochondrial encephalomyopathy. 